WASP-8b

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WASP-8b
Exoplanet Comparison WASP-8 b.png
Size comparison of WASP-8b with Jupiter.
Discovery [1]
Discovered by Cameron et al. (SuperWASP)
Discovery dateApril 1, 2008
Transit
Orbital characteristics [2]
0.0817±0.0006  AU [3]
Eccentricity 0.3057±0.0046
8.158715±0.000016  d
Inclination 88.51°±0.09° [3]
274.21°±0.33°
Semi-amplitude 221.65±1.39  m/s
Star WASP-8
Physical characteristics [3]
Mean radius
1.165±0.032  RJ
Mass 2.216±0.035  MJ
Mean density
1.7370±0.1325  g/cm3
42.5±2.3  m/s2 (4.34 g)
Temperature 1552±85  K (1,279 °C; 2,334 °F) [4]

    WASP-8b is an exoplanet orbiting the star WASP-8A in the constellation of Sculptor. The star is similar to the Sun and forms a binary star with a red dwarf star (WASP-8B) of half the Sun's mass that orbits WASP-8A 4.5 arcseconds away. The system is 294 light-years (90 parsecs ) away and is therefore located closer to Earth than many other star systems that are known to feature planets similar to WASP-8b. The planet and its parent star were discovered in the SuperWASP batch -6b to -15b. On 1 April 2008, Dr. Don Pollacco of Queen's University Belfast announced them at the RAS National Astronomy Meeting (NAM 2008). [5]

    Contents

    Orbit

    The planet orbits WASP-8A at an average distance of just 0.08  AU (12,000,000  km ) and a year passes in slightly more than 8.1 days on WASP-8b, which is somewhat farther from its parent star than other hot Jupiter planets. However, WASP-8b's orbit also has an relatively high eccentricity of 0.3, which, at periastron, brings it as close to its star as said similar planets are.

    One thing that stands out extremely about WASP-8b is its orbit-spin angle to its star of 123°+3.4°
    −4.4°    : This implies that the planet actually orbits retrograde to the spin of the parent star. [6] [1] [7]

    Physical characteristics

    WASP-8b belongs to a class of extrasolar planets known as hot Jupiters and has a mass about 2.2 times and a radius slightly bigger than that of the planet Jupiter. Its density is about 1.737 g/cm3; this implies that, unlike similar close-orbiting gas giants, the planet is actually denser than Jupiter (which has a density of 1.326 g/cm3). [8]

    Owing to its close distance to its star, WASP-8b is extremely hot: Its measured dayside temperature is 1,552 K (1,279 °C), this is even hotter than its equilibrium temperature of 947 K (674 °C). [8] [4]

    See also

    Related Research Articles

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    <span class="mw-page-title-main">WASP-17b</span> Hot-Jupiter exoplanet in the orbit of the star WASP-17

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    <span class="mw-page-title-main">WASP-43b</span> Extrasolar planet in the constellation Sextans

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    WASP-60 is a F-type main-sequence star about 1420 light-years away. The stars age is much younger than the Sun's at 1.7±0.5 billion years. WASP-60 is enriched in heavy elements, having 180% of the solar abundance of iron. The star does not have noticeable starspot activity, an unexpected observation for a relatively young star. The age of WASP-60 determined by different methods is highly discrepant though, and it may actually be an old star which experienced an episode of spin-up in the past.

    WASP-54, also known as BD+00 3088, is a binary star system about 825 light-years away. The primary, WASP-54A, is a F-type main-sequence star, accompanied by the red dwarf WASP-54B on a wide orbit. WASP-54 is depleted in heavy elements, having 55% of the solar abundance of iron. The age of WASP-54 is slightly older than the Sun's at 6.9+1.0
    −1.9     billion years.

    WASP-69, also named Wouri, is a K-type main-sequence star 164 light-years away. Its surface temperature is 4782±15 K. WASP-69 is slightly enriched in heavy elements compared to the Sun, with a metallicity Fe/H index of 0.10±0.01, and is much younger than the Sun at 2 billion years. The data regarding starspot activity of WASP-69 are inconclusive, but spot coverage of the photosphere may be very high.

    WASP-88 is a F-type main-sequence star. Its surface temperature is 6450±61 K. WASP-88 is similar to the Sun in its concentration of heavy elements, with a metallicity Fe/H index of 0.03±0.04, and is younger at an age of 3.0±1.3 billion years.

    WASP-80 is a K-type main-sequence star about 162 light-years away. The star's age is much younger than the Sun's at 1.352±0.222 billion years. WASP-80 is similar to the Sun in concentration of heavy elements, although this measurement is highly uncertain.

    References

    1. 1 2 Didier Queloz; et al. (2010). "WASP-8b: a retrograde transiting planet in a multiple system". Astronomy and Astrophysics. 517: L1. arXiv: 1006.5089 . Bibcode:2010A&A...517L...1Q. doi:10.1051/0004-6361/201014768. S2CID   35774603.
    2. ↑ Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics . 602: A107. arXiv: 1704.00373 . Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882.
    3. 1 2 3 Southworth, J.; Bohn, A. J.; Kenworthy, M. A.; Ginski, C.; Mancini, L. (2020), "A multiplicity study of transiting exoplanet host stars", Astronomy & Astrophysics, 635: A74, arXiv: 2001.08225 , Bibcode:2020A&A...635A..74S, doi:10.1051/0004-6361/201937334, S2CID   210860775
    4. 1 2 Cubillos, Patricio; Harrington, Joseph; et al. (May 2013). "WASP-8b: Characterization of a Cool and Eccentric Exoplanet with Spitzer". The Astrophysical Journal . 768 (1): 42. arXiv: 1303.5468 . Bibcode:2013ApJ...768...42C. doi:10.1088/0004-637X/768/1/42.
    5. ↑ "SuperWASP scoops ten exoplanets in six months". Astronomy Now . 2008-04-01.
    6. ↑ European Southern Observatory. "Artist's impression of an exoplanet WASP 8b in a retrograde orbit".
    7. ↑ Albrecht, Simon; Winn, Joshua N.; Johnson, John A.; Howard, Andrew W.; Marcy, Geoffrey W.; Butler, R. Paul; Arriagada, Pamela; Crane, Jeffrey D.; Shectman, Stephen A.; Thompson, Ian B.; Hirano, Teruyuki; Bakos, Gaspar; Hartman, Joel D. (2012), "Obliquities of Hot Jupiter Host Stars: Evidence for Tidal Interactions and Primordial Misalignments", The Astrophysical Journal, 757 (1): 18, arXiv: 1206.6105 , Bibcode:2012ApJ...757...18A, doi:10.1088/0004-637X/757/1/18, S2CID   17174530
    8. 1 2 Bohn, A. J.; Southworth, J.; Ginski, C.; Kenworthy, M. A.; Maxted, P. F. L.; Evans, D. F. (2020), "A multiplicity study of transiting exoplanet host stars", Astronomy & Astrophysics, 635: A73, arXiv: 2001.08224 , Bibcode:2020A&A...635A..73B, doi:10.1051/0004-6361/201937127, S2CID   210861118

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